zookeeper实战05-zookeeper客户端Curator的使用

zookeeper 的客户端目前主要有三种，一种是原生的方式来操作来操作zookeeper(zookeeper实战04-Java操作zookeeper)、第二种采用开源的zkclient、第三种及本篇所讲的apache官方开源的Curator.

• Curator的优点

1、封装ZooKeeper client与ZooKeeper server之间的连接处理
2、提供了一套Fluent风格的操作API
3、提供ZooKeeper各种应用场景(recipe, 比如共享锁服务, 集群领导选举机制)的抽象封装

• 使用方式

         <dependency>
           <groupId>org.apache.curator</groupId>
            <artifactId>curator-framework</artifactId>
            <version>4.0.0</version>
         </dependency>
         <dependency>
            <groupId>org.apache.curator</groupId>
            <artifactId>curator-recipes</artifactId>
            <version>4.0.0</version>
         </dependency>

基本的curd的使用方式

• 增加节点

        String nodePath = "/super/kkcl";
        byte [] data = "kkcl".getBytes();
        curatorOperator.client.create().creatingParentsIfNeeded()
                .withMode(CreateMode.PERSISTENT)
                .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
                .forPath(nodePath,data);

• 修改节点

    byte [] newData = "newData".getBytes();
    curatorOperator.client.setData().withVersion(0).forPath(nodePath,newData);

• 删除节点

	curatorOperator.client.delete().guaranteed()
    		.deletingChildrenIfNeeded()
            .withVersion(1)
            .forPath(nodePath);

• 读取节点数据

	Stat stat = new Stat();
        byte [] da = curatorOperator.client.getData().storingStatIn(stat).forPath(nodePath);
        System.out.println("节点：" + nodePath + "的数据为：" + new String(da));
        System.out.println("该节点的版本号为：" + stat.getAversion());

• 查询子节点

 	List<String> childNodes = curatorOperator.client.getChildren().forPath(nodePath);
        System.out.println("开始打印子节点");
        for(String s : childNodes){
            System.out.println(s);

• 判断节点是否存在

	Stat stat = curatorOperator.client.checkExists().forPath(nodePath);
        System.out.println(stat);

针对节点的监听

• 分为两种监听的方式：第一种使用一个类去实现watcher,并实现process方法;另一种方式是用一个类实现CuratorWatcher同时实现process方法。

	curatorOperator.client.getData().usingWatcher(new MyCuratorWatcher()).forPath(nodePath);
	curatorOperator.client.getData().usingWatcher(new MyWatcher()).forPath(nodePath);

完整的测试案列

public class CuratorOperator {
    public CuratorFramework client = null;
    public static final String path = "192.168.1.108:2182";

    //实例化zookeeper客户端
    public CuratorOperator(){
        RetryPolicy retryPolicy = new RetryNTimes(3, 5000);
        client = CuratorFrameworkFactory.builder()
                .connectString(path)
                .sessionTimeoutMs(50000).retryPolicy(retryPolicy)
                //.build();
                .namespace("workspace").build();
        client.start();
    }

    //关闭zk客户端连接
    public void closeZKClient(){
        if(client != null){
            this.client.close();
        }
    }

    public static void main(String[] args) throws Exception {
        CuratorOperator curatorOperator = new CuratorOperator();
        boolean isZKCuratorStarted = curatorOperator.client.isStarted();
        System.out.println("当前客户端的状态：" + (isZKCuratorStarted ? "连接中" : "已关闭"));
        String nodePath = "/super/kkcl";
        //创建节点
        byte [] data = "kkcl".getBytes();
        /**
        curatorOperator.client.create().creatingParentsIfNeeded()
                .withMode(CreateMode.PERSISTENT)
                .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)
                .forPath(nodePath,data);
         */

        //更新节点数据
        //byte [] newData = "newData".getBytes();
        //curatorOperator.client.setData().withVersion(0).forPath(nodePath,newData);

        //删除节点
        /**
        curatorOperator.client.delete().guaranteed()
                .deletingChildrenIfNeeded()
                .withVersion(1)
                .forPath(nodePath);
         */

        //读取节点的数据
        /**
        Stat stat = new Stat();
        byte [] da = curatorOperator.client.getData().storingStatIn(stat).forPath(nodePath);
        System.out.println("节点：" + nodePath + "的数据为：" + new String(da));
        System.out.println("该节点的版本号为：" + stat.getAversion());
         */

        //查询子节点
        /**
        List<String> childNodes = curatorOperator.client.getChildren().forPath(nodePath);
        System.out.println("开始打印子节点");
        for(String s : childNodes){
            System.out.println(s);
        }
         */

        //判断节点是否存在
        //Stat stat = curatorOperator.client.checkExists().forPath(nodePath);
        //System.out.println(stat);

        //watcher事件。当使用usingwatcher的时候，监听器只会触发一次，监听完毕就会销毁
        //curatorOperator.client.getData().usingWatcher(new MyCuratorWatcher()).forPath(nodePath);
        //curatorOperator.client.getData().usingWatcher(new MyWatcher()).forPath(nodePath);
        Thread.sleep(3000);
        curatorOperator.closeZKClient();
        boolean isZKCuratorStarted02 = curatorOperator.client.isStarted();
        System.out.println("当前客户端的状态：" + (isZKCuratorStarted02 ? "连接中" : "已关闭"));
    }
}

来源：https://blog.csdn.net/qq_38061755/article/details/99694376